Microsoft will release separate ISOs for the new Windows release
Windows 8.1 Preview won’t be delivered to users exclusively via the Windows Store, as the software maker will also release standalone ISOs available via its official website.Specifically designed to help you set up a dual-boot configuration, these ISOs will allow users to install the operating system on a different partition.
“If you want to install as a dual boot, we do NOT recommend downloading the preview from Windows Store. Installing from the Store will upgrade the existing Windows 8 OS on that partition to Windows 8.1 Preview," Microsoft explains in some leaked documents.
"You will not be given an opportunity to select another partition, so you would need to already have a dual boot system installed in order to install Windows 8.1 Preview as a dual boot through Windows Store.”
Windows 8.1 Preview will be officially unveiled this week and will be distributed via the Windows Store as a free upgrade to all those who have already made the move to Microsoft’s new Windows 8.